(the "release" flag is important due to to a problem of qt debugging libs built for VC++. Otherwise you will have this kind of error : "Microsoft Visual C++ Runtime Library" "runtime error")

Normally your application should be built but before to be able to launch it you have to copy libmarblewidget.dll near your .exe (or to add its path to your system environment path). You also have to copy near your .exe the data\ and plugins\ directories otherwise you will have no maps and no download.

So here it is. You know how to build it in a console!

Building it in Qt Creator should not be very difficult. The important part is to configure your project to call ming32-make with the "release" flag :

Then you should be able to use Qt Creator as usual.

The next step you could want to do is to use marble widget plugin in Qt Designer.

(Note: here is how to use it in Qt Designer in standing alone; not the version embedded in Qt Creator.
I have tried every configuration without being able to make it work that way.
So here is only the way to do it in Qt Designer directly).

When you have installed Marble It should have copy the needed plugins in "C:\Qt\2010.02.1\qt\plugins\designer" but those plugins need libmarblewidget.dll to be accessible. So, like what we did for your application, we need to copy libmarblewidget.dll and "data\" next to "C:\Qt\2010.02.1\qt\bin\designer.exe" ( and eventually "plugins\" if we want to be able to download tiles when using marble widget in Qt Designer... ). Once this is done, you should have Marble's plugins available in Qt Designer: